Wireless Communication System

ABSTRACT

A wireless communication method used by a wireless communication apparatus is disclosed. The wireless communication method transmits and receives control information divided into a second control information containing information related to the demodulation and decoding of traffic channel and a first control information containing information related to the MIMO separation of the second control information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a wireless communicationsystem and a wireless communication apparatus included therein thatcommunicates data, and more particularly, to a wireless communicationsystem and a wireless communication apparatus included therein havingone or more antenna.

2. Description of the Related Art

A conventional wireless communication apparatus generally has an antennafor transmission and an antenna for reception, or a single antenna fortransmission and reception. A wireless communication apparatus havingmultiple antennas using space-diversity reception techniques is known. Awireless communication system is also known as a Multiple Input MultipleOutput (MIMO) system in which both a transmitting apparatus and areceiving apparatus are provided with multiple antennas, and thetransmitting apparatus and the receiving apparatus communicate usingspace division multiplexing techniques in accordance with the number ofantennas. Multiple data streams are transmitted between the multipleantennas of the transmitting apparatus and those of the receivingapparatus using space division multiplexing techniques throughindependent multiple channels. Various techniques of MIMO are underdevelopment (see reference documents No. 1 through 4, for example).

Technique for a MIMO wireless communication system is proposed in whicheach data stream is adaptively controlled such that the transmissionrate thereof becomes optimal (see reference document No. 5, forexample). A wireless communication system using Wideband-Code DivisionMultiple Access (W-CDMA) is known in which data is transmitted bymodulating and multiplexing each channel with spreading code. ThisW-CDMA technique has been already used for wireless communicationsbetween a cellular phone and a base station, for example.

High Speed Downlink Packet Access (HSDPA) is defined that enables theW-CDMA system to transmit data at 14 Mbps or less through a downlink.This system employs adaptive encoding modulation system for packettransmission, in which Quadrature Phase Shift Keying (QPSK) andQuadrature Amplitude Modulation (16 level QAM), for example, areadaptively switched, such that transmission rate can be adapted to thecondition of wireless transmission channel.

The HSDPA employs Hybrid Automatic Repeat Request (H-ARQ). For example,if a mobile terminal detects an error in data received from a basestation, the mobile terminal requests the base station to re-transmitthe data. The base station re-transmits the data in response to receiptof the request. The mobile terminal uses both of the original data andre-transmitted data to perform error correction.

An example of wireless channel used in the HSDPA system includes HighSpeed-Shared Control Channel (HS-SCCH), High Speed-Physical DownlinkShared Channel (HS-PDSCH), (High Speed-Dedicated Physical ControlChannel).

The wireless channels HS-SCCH and HS-PDSCH are common channels(downlink) from a base station to a mobile terminal of a mobile wirelesscommunication system. HS-SCCH is a control channel through which variousparameters related to data transmitted through HS-PDSCH are transmitted.An example of the parameters includes modulation type informationindicating modulation method by which data is transmitted usingHS-PDSCH, the number of spreading codes, the pattern information of ratematching processing performed on transmission data.

HS-DPCCH is a individual control channel (uplink) from the mobileterminal to the base station of the mobile wireless communicationsystem. The HS-DPCCH transmits ACK signal or NACK signal from the mobileterminal to the base station, which indicates whether data is correctlyreceived through the HS-PDSCH. For example, if CRC error is detected inthe received data, a NACK signal is transmitted to the base station. Inresponse to receipt of the NACK signal, the base station re-transmitsthe data. HS-DPCCH is used to periodically transmit the result ofmeasurement on the condition of received signal from the base station(Signal to Interference Patio (SIR), for example) as a Channel QualityIndicator (CQI). The base station determines whether the condition ofdownlink wireless channel is satisfactory. If satisfactory, the basestation changes the modulation method to a modulation method with whichdata can be transmitted at higher speed. If not satisfactory, the basestation changes the modulation method to a modulation method with whichdata is transmitted at lower speed.

FIG. 15 is a schematic diagram for explaining the channel structure ofthe HSDPA. In FIG. 15, CPICH, P-CCPCH, HS-SCCH, HS-PDSCH, and HS-DPCCHare schematically shown. Common Pilot Channel (CPICH) and Primary CommonControl Physical Channel (P-CCPCH) are downlink common channels. TheCPICH is used for channel estimation, cell search, and timing of otherdownlink physical channels in the same cell. The CPICH is a channelthrough which so-called pilot signals are transmitted. The P-CCPCH is achannel through which notice information is transmitted. The HS-SCCH,HS-PDSCH, HS-DPCCH are control channels described above. The above CQIand ACK/NACK are transmitted through the HS-DPCCH.

Fifteen slots form one frame (10 ms). Because the CPICH is used as thereference of timing, the heads of the P-CCPCH and HS-SCCH match the headof the CPICH in timing. However, the head of the HS-PDSCH lags behindthe other channels by two slots. This lag allows a mobile terminal toreceive information required for the demodulation of the HS-PDSCH. Thatis information related to modulation and spreading code is transmittedthrough the HS-SCCH before the demodulation and decoding of theHS-PDSCH. In HS-SCCH and HS-PDSCH, three slots form one sub-frame.

According to 3GPP TS25.212 v.5.7.0, the following information aretransmitted through the HS-SCCH:

(a) Channelization Code Set Information (Xccs): 7 bits, information ofspreading code used for the HS-DSCH;

(b) Modulation Scheme Information (Xms): 1 bit, demodulation techniqueused for the HS-DSCH;

(c) Transport-Block Size Information (Xtbs): 6 bits, the block size oftransmission data converted into error correction code;

(d) Hybrid-ARQ Process Information (Xhap): 3 bits, process number forre-transmission;

(e) Redundancy and Constellation Version (Xrv): 3 bits, a parameter forrate matching;

(f) New Data Indicator (Xnd): 1 bit, information indicating new data;and

(g) UE Identity (Xue): 16 bits, user identification information.

The information transmitted through the HS-SCCH has 37 bits. Thisinformation allows the mobile terminal to learn the parameter ofmodulation technique, spreading code, error correction used in theHS-DSCH. As a result, the mobile terminal can demodulate and decodeHS-DSCH based on these parameters.

The (a) Xccs indicates spreading code used for the transmission of datathrough HS-PDSCH, such as a combination of the number of multicodes andcode offset. The (b) Xms indicates which modulation technique, QPSK or16 level QAM, is used by “1” and “0”. The (c) Xtbs is data forcalculating the size of data transmitted by one sub-frame of HS-PDSCH.The (d) Xhap indicates the process number of H-ARQ, which is a serialnumber of transmitted data block. When data is re-transmitted, the sameprocess number as the previous transmission data is used.

The (e) Xry indicates the redundancy version parameter and constellationparameter of HS-PDSCH in re-transmission. A determination is made ofwhether the parameters are updated depending on the case of transmissionand re-transmission. The (f) Xnd indicates whether a transmission blockof HS-PDSCH is new block or re-transmitted block. If new block, Xndalternates between “1” and “0”. If re-transmitted block, Xnd is the sameas that of the original block. The (g) Xue is the identificationinformation of a mobile terminal (user).

The reception of HS-SCCH allows the mobile terminal to know theparameters of modulation technique, spreading code, and error correctionused in HS-PDSCH and to demodulate and decode the HS-PDSCH.

The following documents are cited for reference: (1) Japanese PatentLaid-Open Application No. 2004-135304; (2) Japanese Patent Laid-OpenApplication No. 2003-338779; (3) Japanese Patent Application No.2003-332963; (4) Ari Hottinen, Olav Tirkkonen, Risto Wichman,“Multi-antenna Transceiver Techniques for 3G and Beyond”; (5) 3GPP TS25.211 v5.5.0 (3^(rd) Generation Partnership Project; TechnicalSpecification Group Radio Access Network; Physical channels and mappingof transport channels onto physical channels (FDD)); (6) 3GPP TS 25.213v5.5.0 (3^(rd) Generation Partnership Project; Technical SpecificationGroup Radio Access Network; Spreading and modulation (FDD)); and (7)3GPP TS 25.214 v5.7.0 (3^(rd) Generation Partnership Project; TechnicalSpecification Group Radio Access Network; Physical layer procedures(FDD)).

The number of bits required for the above parameters (a) Xccs, (b) Xms,(c) Xtbs, (d) Xha, (e) Xrv, (f) Xnd, and (g) Xue, in the case in whichthe HSDPA system is adapted to the MIMO system, are shown in FIG. 16 fora mode in which MIMO is not used, a N multiplexing 1 packet mode inwhich MIMO is used, and a N multiplexing stream independent mode inwhich MIMO is used. In FIG. 16, N means the number of MIMO multiplexing,and [log 2 (N)] means the least integer equal to or more than N.

The above N multiplexing 1 packet mode is a mode in which a packet isdivided into data, and each item of the data is transmitted through oneof N paths formed by the MIMO multiplexing. The above N multiplexingstream independent mode is a mode in which different packets aretransmitted through N paths, respectively, formed by the MIMOmultiplexing.

In the MIMO N multiplexing stream independent mode, differenttransmission technique can be applied to each path. As a result, if thenumber of MIMO multiplexing N increases, the amount of informationconsiderably increases. If the resource (time, frequency, and spreadingcode, for example) is allocated in advance in accordance with theestimated maximum amount of control information, when the MIMOmultiplexing N increases, remaining resource is reduced, which mayresult in decrease in throughput. On the other hand, if MIMOmultiplexing is used for increasing the number of bits transmitted asthe control information, even a user in a wireless transmissionenvironment where MIMO multiplexing is not suitable is required toreceive control information containing many bits, which may increaseerror rate of received control information.

If the power of control channel is increased in order to improvetransmission quality, interference with other channels may consequentlyincrease, which results in reduction in the throughput of a wirelesscommunication system. In addition, not all mobile terminals in a mobilephone system usually support MIMO function. There are mobile terminalssupporting MIMO function and mobile terminals not supporting MIMOfunction in such a mobile phone system, which means that the controlchannel can not always be transmitted using MIMO system. Furthermore,the traffic channel and the control channel need to be controlled tooptimize transmission quality. However, if it is desired to increase theinformation amount of control channel by changing the rate of errorcorrection encoding without using MIMO, the control of the trafficchannel and the control channel becomes very difficult because thetransmission rate of MIMO multiplexed traffic channel is increased.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providea novel and useful wireless communication in which one or more of theproblems described above are eliminated.

Another and more specific object of the present invention is to providea wireless communication system and apparatus (for example, base stationand mobile terminal) that, even if the amount of information related tothe transmission of data is increased, can flexibly transmit theinformation related to the transmission of data regardless of the use ofthe MIMO N multiplexing stream independent mode.

To achieve at least one of the above objects, according to an aspect ofthe present invention, a wireless communication system including a MIMOwireless communication apparatus that can communicate through aplurality of antennas and a non-MIMO wireless communication apparatus (awireless communication apparatus that does not use MIMO) that cancommunicate through a single antenna or a plurality of antennas, whereinthe MIMO wireless communication apparatus includes a communication unitconfigured to transmit and receive control information divided into asecond control information containing information related to thedemodulation and decoding of traffic channel and a first controlinformation containing information related to the MIMO separation of thesecond control information.

According to another aspect of the present invention, a MIMO wirelesscommunication apparatus having multiple antenna may include acommunication unit configured to divide control information including atleast information related to the MIMO separation of data of trafficchannel into second control information including at least informationrelated to the MIMO separation of the traffic channel and first controldata including information related to whether MIMO is used andinformation related to the MIMO separation of the second controlinformation, multiplex the control information with the data of thetraffic channel, process the multiplexed signal for multiple antennas,and the communication unit further separates reception signalcorresponding to the multiple antennas, in accordance with the number ofMIMO multiplexing.

Other objects, features, and advantages of the present invention will bemore apparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a wireless communication systemaccording to an embodiment of the present invention;

FIG. 2 is a block diagram showing a transceiver unit according to anembodiment of the present invention;

FIG. 3 is a block diagram showing a traffic channel transmission symbolgeneration unit according to an embodiment of the present invention;

FIGS. 4A through 4C are schematic diagrams for explaining the MIMOseparation of traffic channels according to an embodiment of the presentinvention;

FIG. 5 is a block diagram showing a transmission unit that transmitscontrol information according to an embodiment of the present invention;

FIG. 6 is a schematic diagram showing the structure of flames accordingto an embodiment of the present invention;

FIGS. 7A and 7B are schematic diagrams for explaining operation modes,control information, and traffic channels according to an embodiment ofthe present invention;

FIGS. 8A and 8B are schematic diagrams for explaining operation modes,control information, and traffic channels according to an embodiment ofthe present invention;

FIGS. 9A through 9C are schematic diagrams for explaining a CRCattachment unit according to an embodiment of the present invention;

FIG. 10 is a block diagram showing a transceiver unit having an errorcheck unit according to an embodiment of the present invention;

FIG. 11 is a block diagram showing a transceiver unit having an errorcheck unit according to another embodiment of the present invention;

FIG. 12 is a block diagram showing a transceiver unit having an errorcheck unit according to yet another embodiment of the present invention;

FIG. 13 is a schematic diagram for explaining the allocation of time andfrequency to first control information and second control informationaccording to an embodiment of the present invention;

FIG. 14 is a block diagram showing a transceiver unit according to anembodiment of the present invention;

FIG. 15 is a schematic diagram for explaining the structure of channelsin accordance with HSDPA technique; and

FIG. 16 is a schematic diagram for explaining the relation between thenumber of MIMO multiplexing and control information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment of the present invention are described belowwith reference to the drawings.

Referring to FIG. 1, a wireless communication system according to thepresent invention includes MIMO wireless communication apparatuses 1 a,1 b that can communicate through a plurality of antennas 2 a, 2 b and anon-MIMO wireless communication apparatus 1 c that can communicatethrough a single antenna or a plurality of antennas 2 c. The MIMOwireless communication apparatus 1 a, 1 b includes a communication unit(transmission/reception unit 3 a, 3 b and signal processing unit 4 a, 4b) configured to transmit and receive control information divided into asecond control information containing information related to thedemodulation and decoding of traffic channel and a first controlinformation containing information related to the MIMO separation of thesecond control information.

In other words, the wireless communication apparatus 1 a includes atransmission processing unit (corresponding to transmission/receptionunit 3 a and signal processing unit 4 a) configured to transmit firstcontrol information, second control to which transmission processing inaccordance with the first control information is applied, thetransmission rate of the second control information being changeable,and data to which transmission processing in accordance with at leastthe second control information is applied.

That is, the wireless communication apparatus 1 a transmits the firstcontrol information before transmitting data (preferably using MIMOmultiplexing) through a common channel. The first control informationincludes information related to the transmission of the second controlinformation processed in accordance with the first control information(for example, information about MIMO multiplexing, modulation technique,rate matching processing, encoding. The first control information allowsthe transmission rate of the second control information to be variable.The second control information includes information related to thetransmission of data processed in accordance with the second controlinformation through a common channel, for example, in the same manner.Preferably, the second control information is transmitted after thebeginning (or completion) of the transmission of the first controlinformation. According to another embodiment, however, the secondcontrol information can be transmitted at the same time when the firstcontrol information is transmitted.

If information related to the transmission of data to be transmittedthrough a common channel can be transmitted as a part of the firstcontrol information (for example, in the case of MIMO N multiplexing 1packet mode and the amount of information is small), the second controlinformation does not need to be transmitted. If the amount ofinformation is large (for example, in the case of MIMO N multiplexingstream independent mode), the second control information as well as thefirst control information is preferably transmitted.

According to the above arrangements, the transmitting wirelesscommunication apparatus 1 b (a reception processing unit correspondingto the transmission/reception unit 3 b and the signal processing unit 4b) can identify how the second control information has been transmittedbased on the received first control information, and receive the secondcontrol information. The reception of the second control informationallows the wireless communication apparatus 2 b to identify how the datais transmitted and receive the data.

The first control information can include information related to how thedata has been transmitted. The receiving wireless communicationapparatus 1 b can receive the data using both the first and secondcontrol information.

In addition, the first control information can include informationindicating whether MIMO multiplexing is used for the first transmissionof the second control information (and the second transmission of thedata). The receiving wireless communication apparatus can learn whetherMIMO multiplexing is used for the first transmission of the secondcontrol information based on the first control information, and receivethe second control information that is MIMO multiplexed. The firstcontrol information can further include identification information ofthe receiving wireless communication apparatus 1 b. The identificationinformation may be multiplied to the transmission signal.

The wireless communication apparatus according to the present inventionmay include a communication unit (transmission/reception unit 3 a, 3 band signal processing unit 4 a, 4 b) configured to divide controlinformation including at least information related to the MIMOseparation of data of traffic channel into second control informationincluding at least information related to the MIMO separation of thetraffic channel and first control data including information related towhether MEMO is used and information related to the MIMO separation ofthe second control information, multiplex the control information withthe data of the traffic channel, process the multiplexed signal formultiple antennas 2 a, 2 b, and the communication unit further separatesreception signal corresponding to the multiple antennas 2 a, 2 b, inaccordance with the number of MIMO multiplexing.

The wireless communication system is characterized in that controlinformation required for the reception, demodulation, decoding oftraffic channel is divided into first control information and secondcontrol information, and transmitted between wireless communicationapparatuses. A non-MIMO wireless communication apparatus can receive,demodulate, and decode data of the traffic channel in accordance withparameters transmitted as the first control information. A MIMO wirelesscommunication apparatus can separate the second control informationbased on the first control information (MIMO separation), and separate,demodulate, and decode the MIMO multiplexed data of the traffic channelin accordance with the second control information. According to theabove arrangements, the transmission of control signal does not requiremore physical resource than the case the MIMO multiplexing is not used.The present invention is applicable to both the case in which multiplepackets are transmitted using MIMO multiplexing and the case in which alarge block sized packet is transmitted using MIMO multiplexing. Thepresent invention can be adapted even if the number of MIMO multiplexingis varied.

In addition, the first control information, the second controlinformation to which first transmission processing in accordance withthe first control information is applied, the transmission rate of thesecond control information is variable, data to which secondtransmission processing in accordance with the second controlinformation is applied are transmitted. As a result, even if the amountof information related to the transmission of data is large, theinformation can be transmitted as the second control information thetransmission rate of which is variable.

FIG. 1 is a schematic diagram showing a wireless communication systemaccording to an embodiment of the present invention. The wirelesscommunication system shown in FIG. 1 includes two MIMO wirelesscommunication apparatuses 1 a and 1 b, and non-MIMO wirelesscommunication apparatus 1 c. This wireless communication system supportsthe High Speed Downlink Packet Access (HSDPA). The MIMO wirelesscommunication apparatuses 1 a and 1 b have multiple antennas 2 a or 2 b,respectively. Each of the multiple antennas 2 a (2 b) may be used bothfor transmission and reception. Alternatively, one or more of themultiple antennas 2 a (2 b) may be used for transmission and the othermay be used for reception. The non-MIMO wireless communication apparatus1 c has a single antenna 2 c both for transmission and reception, or hastwo antennas (not shown) for transmission and reception, respectively.The MIMO wireless communication apparatus 1 a and 1 b having themultiple antennas can be switched to non-MIMO wireless communicationapparatuses. Each of the wireless communication apparatuses 1 a-1 c hasa transmission/reception unit 3 a-3 c and a signal processing unit 4 a-4c. The transmission/reception unit 3 a-3 c and the signal processingunit 4 a-4 c constitute a communication unit of the wirelesscommunication apparatus 1 a-1 c.

The wireless communication apparatuses 1 a-1 c form a mobile wirelesscommunication system in which the MIMO wireless communication apparatus1 a is a base station, the MIMO wireless communication apparatus 1 b isa mobile station, and the non-MIMO wireless communication apparatus 1 cis another mobile station. The wireless communication apparatus 1 a isconnected to an external network (not shown), and is wirelesslycommunicably connected to the MIMO wireless communication apparatus 1 band the non-MIMO wireless communication apparatus 1 c. The MIMO wirelesscommunication apparatus 1 b and the non-MIMO wireless communicationapparatus 1 c can communicated with other communication apparatuses (notshown) connected to the external network via the MIMO wirelesscommunication apparatus that operates as the base station in its servicearea.

The signal processing unit 4 a and 4 b of the MIMO wirelesscommunication apparatus 1 a and 1 b supports MIMO separation functionand MIMO decode function. The MIMO separation function is a function ofthe signal processing unit 4 a and 4 b that separates transmissionsignals for the multiple antennas 2 a and 2 b, and inputs the separatedtransmission signals to the transmission/reception unit 3 a and 3 b. TheMIMO decode function is a function of the signal processing unit 4 a and4 b that decodes reception signals received by thetransmission/reception unit 3 a and 3 b through the multiple antennas 2a and 2 b. The signal processing unit 4 a and 4 b has a traffic channel,a control channel, and a pilot channel, for example. The signalprocessing unit 4 a and 4 b transmits and receives signals bymultiplexing them in accordance with transmission procedures.

Physical resource allocated to the control channel among the wirelesscommunication apparatuses 1 a-1 c is divided into two domains. Thecontrol information is also divided into first control information C1and second control information C2. The first control information C1 andthe second control information C2 are allocated to the two domains ofthe physical resource. An example of the domains of the physicalresource includes the domains of time, the domains of frequency, thedomains of time and frequency, spreading codes in the case of CDMAsystem, sub-carriers in the case of OFDM. The first control informationmay be MIMO-based and the second control information C2 may benon-MIMO-based.

The first control information C1 includes the above-mentioned (g) Xue,that is, the user identification information (UE identity) andinformation indicating whether the second control information isMIMO-based. The second control information C2 includes the MIMO mode ofthe traffic channel and information that may increase or be reduceddepending on re-transmission control and adaptive modulation control,for example. If much control information is required for MIMOmultiplexing, transmission rate is increased by MIMO multiplexing thesecond control information C2. If much control information is notrequired for MIMO multiplexing, the transmission rate is reduced withoutMIMO multiplexing the second control information C2. The signalprocessing unit 4 a and 4 b may perform processing described above. Thesignal processing unit 4 a-4 c may be provided with a unit that attachescyclic redundancy check (CRC) to the first control information C1, thesecond control information C2, or both. The signal processing unit 4 a-4c may also include a unit that checks the attached CRC, and a unit thatreturns the result of the CRC to a wireless communication apparatus atthe transmission side. Processing of the signal processing unit 4 a-4 cmay be performed by the arithmetic operation of a Digital SignalProcessor (DSP), for example.

According to the above arrangements, the non-MIMO wireless communicationapparatus 1 c suffices to receive the first control information C1, (Thenon-MIMO wireless communication apparatus 1 c can receive the secondcontrol information and use it for receiving data through the trafficchannel.) The MIMO wireless communication apparatuses 1 a and 1 breceive the first control information C1, and use the received firstcontrol information C1 for receiving and separating the second controlinformation C2 which is MIMO multiplexed. The MIMO wirelesscommunication apparatuses 1 a and 1 b receive data through the trafficchannel which is MIMO multiplexed in accordance with information relatedto demodulation and decoding contained in the second control informationC2. Thus, the control information is divided into the first controlinformation C1 and the second control information C2, which containappropriate information, and MIMO frames can use the same structure asnon-MIMO frames do. According to the above arrangements, multiple userscan use MIMO multiplexing without changing the allocation of resourcessuch as frame structure, frequency, time, and spreading codes, resultingin increase in the efficiency of resource usage. In addition, themaximum number of MIMO multiplexing can be changed. As a result, if thewireless communication system is enhanced and the maximum number ofmultiplexing is increased, the wireless communication system accordingto the present embodiment can be adapted at high flexibility.

FIG. 2 is a block diagram showing a communication unit corresponding toan antenna i (i=1˜m) of the multiple antennas 2 a, 2 b, and 2 c. Thecommunication unit includes spreading units 11-1, 11-2, 11-3, anaddition unit 12, and a wireless transmission unit 13. Antenna itransmission symbol (TC(i)) of the Traffic Channel (TC) is input to thespreading unit 11-1. Antenna i transmission symbol (CC(i)) is input tothe spreading unit 11-2. Antenna i Pilot symbol (P8i)) is input to thespreading unit 11-3. The spreading unit 11-1, 11-2, 11-3 multiplesspreading codes for discriminating multiple channels to input dataseries. Assuming A (k X Tchip) is spreading code pattern, B (n XTsymbol) is input symbol, C (k X Tchip) is spread codes and Tsymbol=NSFX Tchip, then C (k X Tchip) B (int(k/NSF) X NSF X Tchip) X A (k XTchip). The addition unit 12 adds the multiple spread codes for eachchip and input the result to the wireless transmission unit 13. Thewireless transmission unit 13 shifts central frequency to apredetermined frequency, amplitudes the power of the spread codes, andtransmits the spread codes through the antenna i.

FIG. 3 is a block diagram showing a transmission symbol generation unitof the traffic channel (TC). In FIG. 3, 15 denotes a CRC attachmentunit, 16 denotes an error correction coding unit, 17 denotes a symbolmapping unit, and 18 denotes a MIMO separation unit. The transmissionsymbol generation unit generates transmission symbols corresponding toeach antenna i (i=1˜m). The transmission symbol generation unit is apart of the signal processing unit 4 a, 4 b, and 4 c. The CRC attachmentunit 15 attaches error detection information (CRC) to transmission dataseries D1 that is transmitted as a single packet thereby to form a dataseries D2. The generation and attachment of CRC is irrelevant to theessence of the present embodiment, and therefore their description isnot given here in detail. For example, a CRC attachment unit describedin connection with W-CDMA in chapter 4.2.1 “CRC attachment” of TS25.212v5.7.0 can be used.

The error correction encoding unit 16 converts the data series D2 towhich the error detection information (CRC) is attached into errorcorrection code. This error correction encoding is irrelevant to theessence of the present embodiment, and therefore their description isnot given here in detail. For example, convolutional code and turbo codedescribed in chapters 4.2.3.1 and 4.2.3.2 of TS25.212 v5.7.0 may be usedas the error correction encoding unit.

The symbol mapping unit 17 performs symbol mapping of the data series D3that is error correction encoded to QPSK and 16QAM, for example. Theresult of symbol mapping is input to the MIMO separation unit 18 as thesymbol series D4. In the case of QPSK, for example, each 2 bits of inputD3=(b0, b1) is mapped to one symbol (I, Q). For example, if b0 and b1are either 0 or 1, (b0, b1) may be mapped to (I, Q), where I=1−2×b0, andQ=1−2×b1.

In the case of 16QAM, for example, 4 bits of D3=(b0, b1, b2, b3) may bemapped to (I, Q), where I=(1−2×b0)*(2−(1−2×b2)), andQ=(1−2×b0)*(2−(1−2×b2)).

The MIMO separation unit 18, in the case of non-MIMO, outputs D4 toTC(1), but outputs no data to TC(2)˜TC(Ntxant). That is, the MIMOseparation unit 18 outputs the transmission data series for a singleantenna. In the case of MIMO multiplexed, D4-1, D4-2, . . . , D4-Ntxantare generated by symbol mapping from the multiple blocks of the errorcorrection encoding unit 16 using the symbol mapping unit 17. TC(i)=D4−iis transmitted using the i^(th) stream (i=1, 2, . . . , Ntxant) of MIMOmultiplexed data stream.

The traffic channel (TC) has three MIMO modes 1-3 (non-MIMO, MIMO-basedN multiplexed 1 packet mode, and MIMO-based N multiplexed streamindependent mode). In the mode 1, a wireless communication apparatusthat does not support MIMO technology or a non-MIMO wirelesscommunication apparatus transmits one packet using a single stream. Inmode 2, a MIMO wireless communication apparatus transmits one MIMOmultiplexed packet using n streams. Although the amount of transmissiondata is increased, the amount of the control information does notchange. In mode 3, stream independent adaptive modulation andre-transmission control are performed during MIMO multiplexing. A MIMOwireless communication apparatus transmits an independent packet foreach stream. Since the packets are independent, control information isrequired for each packet, resulting in the increase in controlinformation amount.

FIGS. 4A-4C are schematic diagrams for explaining the encoding and MIMOseparation of traffic channel, each corresponding to respective mode1-3. The encoding and MIMO separation of traffic channel is performed bythe signal processing unit 4 a-4 c shown in FIG. 1.

FIG. 4A shows processing of mode 1. The CRC attachment unit 15 (FIG. 3)receives the data series D1 of the traffic channel and attaches theerror detection information CRC thereto thereby to form the data seriesD2. The error correction encoding unit 16 receives the data series D2and converts the received data series D2 into error correction codethereby to form the data series D3. The symbol mapping unit 17 receivesthe data series D3 and outputs TC(1) corresponding to the trafficchannel (TC), but outputs no signal to TC(2)-TC(Ntxant) because MIMO isnot used in this case.

FIG. 4B shows processing of mode 2, in which MIMO multiplexing isapplied thereby forming a single packet. The CRC attachment unit 15receives the data series D1 of the traffic channel and attaches theerror detection information CRC thereto thereby to form the data seriesD2. The error correction encoding unit 16 receives the data series D2and converts the received data series D2 into error correction codethereby to form the data series D3. The symbol mapping unit 17 and aserial/parallel conversion unit receives the data series D3 and outputsTC(1)-TC(Ntxant) corresponding to the traffic channel (TC).

FIG. 4C shows processing of mode 3. In mode 3, an independent packet istransmitted for each stream. Different error detection information CRCmay be attached to each stream, and different error correction encodingis performed for each stream. Since different modulation is performedfor each stream, different symbol mapping is performed thereby to outputTC(1)-TC(Ntxant).

FIG. 5 is a schematic diagram showing a transmission symbol generationunit that generates control information corresponding to antennas. Thetransmission symbol generation unit is a part of the signal processingunit 4 a-4 c shown in FIG. 1. The transmission symbol generation unitincludes a time multiplexing unit 21 and a MIMO separation unit 22.

When the MIMO separation is ON, the control information CC is dividedinto first control information C1 and second control information C2. Thefirst control information C1 is input to the time multiplexing unit 21,and the second control information is input to the MIMO separation unit22. The second control information C2 is separated to C2(1)-C2(Ntxant).C2(1) is input to the time multiplexing unit 21 and multiplexed with thefirst control information C1 thereby to form CC(1). C2(2)-C2(Ntxant) areoutput as CC(2)-CC(Ntxant), respectively. Since CC(1) needs to bereceived by non-MIMO wireless communication apparatus, CC(1) ispreferably output through a predetermined antenna. However, according toanother embodiment, CC(1) may be transmitted through another antennathat is adaptively determined.

If the MIMO multiplexing is to be performed (MIMO separation is ON), theMIMO separation unit 22 performs MIMO separation of the second controlinformation C2 by serial/parallel conversion of the input second controlinformation C2 into multiple signal series CC(1)-CC(Ntxant). The signalseries CC(1) among the multiple signal series is input to the timemultiplexing unit 21. If the MIMO multiplexing is not to be performed(MIMO separation is OFF), the input second control information C2 isoutput as a signal series CC(1) as is, and the output signal seriesCC(1) is input to the time multiplexing unit 21.

FIG. 6 is a schematic diagram showing a frame including controlinformation CC, the data of traffic channel TC, and pilot channel, whichare time multiplexed. The control information is divided into firstcontrol information C1 and second control information C2 as describedabove.

FIG. 7A shows relation between the classification of control informationand the number of allocated bits. FIG. 7B shows correspondence amongoperation mode, the second control information C2, and the trafficchannel TC. FIG. 7A includes the first control information C1, thesecond control information C2, and the traffic channel TC, as thechannel and further includes information indicating whether to performMIMO multiplexing, information content to be contained in each channel,and the number of bits allocated for each mode and each channel. Thefirst control information C1 is not MIMO multiplexed. The informationcontent of the first control information C1 includes user identificationinformation USER-ID and the MIMO-mode (M1) of the second controlinformation C2. The number of bits required for the user identificationinformation USER-ID is 16 bits for any mode, and the number of bitsrequired for the MIMO-mode (M1) of C2 is the number of MIMO multiplexingfor any mode. “1” in a bit i indicates that the i^(th) stream exists.

The second control information C2 is separated the MIMO separation unit22 shown in FIG. 5 in accordance with MIMO separation informationcontained in the first control information. The information content ofthe second control information C2 includes decoding information,demodulation information, and MIMO-mode (M2) of the traffic channel. Thenumber of bits required for the MIMO-mode (M2) of the traffic channel TCis the number of MIMO multiplexing, N, for any mode. The number of bitsrequired for the decoding information and the demodulation informationfor mode 3 is N times as many as those for mode 1 and 2.

Whether the traffic channel TC is MIMO multiplexed or not is determinedby the second control information C2. As described above, the controlinformation the amount of which changes depending on the mode isincluded in the second control information C2.

According to another embodiment, various systems such as transmissiondiversity mode may be adapted to the MIMO multiplexing system. In such acase, information indicating that the transmission diversity mode isadapted can be included in the MIMO-mode (M1) of the second controlinformation C2 or the MIMO-mode (M2) of the traffic channel TC. Thenumber of bits of the M1 and M2 may be included in the first controlinformation C1 as they are not dependent on the modes. In this case, theamount of the second control information C2 is proportional to thenumber of MIMO multiplexing. According to the above arrangements, theamount of the first control unit C1 does not change but the amount ofthe second control information C2 changes as the number of MIMOmultiplexing changes, resulting in increase in transmission efficiency.

FIG. 7B shows whether the second control information C2 and the trafficchannel TC are MIMO multiplexed (MIMO) or not (normal) for each mode1-3. If MIMO multiplexed, adaptive modulation is required for eachantenna, which results in increase in the amount of control information.If the second control information C2 is MIMO multiplexed, the amount ofthe control information can be increased without changing the allocationof physical resource.

FIG. 8A shows relation between the classification of control informationand the number of allocated bits, and FIG. 8B shows correspondence amongthe operation mode, the second control information C2, and the trafficchannel TC. FIG. 8A is different from FIG. 7A in that the MIMO-mode (M2)of the traffic channel TC, which is included in the second controlinformation C2 in FIG. 7A, is included in the channel C1 as “MIMO-mode(M1) of C2 and TC”. If the control information C2 and the trafficchannel TC are multiplexed using the same MIMO-mode (M2) the MIMO-mode(M2) of the TC does not need to be included in the second controlinformation C2, which results in that the relation between the channeland the number of bits shown in FIG. 8A can be used.

FIG. 8B shows the case in which the second control information C2 andthe traffic channel TC use the same mode. In FIG. 7B, the second controlinformation C2 indicates normal for the mode 2 and the traffic channelTC indicates MIMO for the mode 2. In FIG. 8B, however, both the secondcontrol information C2 and the traffic channel TC indicate MIMO for themode 2. According to this arrangement, the amount of control informationcan be reduced, and reception processing can be made simple.

FIGS. 9A-9C show schematic diagrams for explaining the attachment oferror detection code CRC. In FIGS. 9A-9C, 31 and 32 denote the CRCattachment unit, 33 and 34 denote the symbol mapping unit, and 35 denotedomain allocation processing unit. The attachment is performed by thesignal processing unit 4 a-4 c shown in FIG. 1. FIG. 9A shows the casein which CRC is generated and attached to the first control informationC1 by the CRC attachment unit 31. The first control information C1 towhich the CRC is attached is input to the symbol mapping unit 33. Thesecond control information C2 is input to the symbol mapping unit 34 asis. Signal series after mapping are input to a domain allocationprocessing unit 35, and allocated to the physical channel domains.

FIG. 9B shows the case in which the first control information C1 isdirectly input to the symbol mapping unit 33. CRC is generated andattached to the second control information C2 by the CRC attachment unit32, and the second control information to which the CRC is attached isinput to the symbol mapping unit 34. The first and second controlinformation C1 and C2 are allocated to the physical channel domainsafter symbol mapping.

FIG. 9C shows the case in which the first control information C1 towhich CRC is attached by the CRC attachment unit 31 is input to thesymbol mapping unit 33, and the second control information C2 to whichCRC is attached by the CRC attachment unit 32 is input to the symbolmapping unit 34. The first and second control information C1 and C2 areallocated to the physical channel domains by the domain allocationprocessing unit 35 after symbol mapping.

As described above, CRC can be attached to the first control informationC1, the second control information C2, or both. In the case in which thefirst control information C1 to which CRC is attached is transmitted, areceiving wireless communication apparatus can perform error detectionon the received first control information C1 using the CRC, and returnACK or NACK to a transmitting wireless communication apparatus inaccordance with the result of the error detection. In such a case, ifNACK is returned, which means that correct control information can notbe transmitted, the transmitting wireless communication apparatus stopstransmitting the second control information C2 and the traffic channelTC, and re-transmits the first control information C1.

In the case in which the second control information C2 to which the CRCis attached is transmitted, ACK and NACK can be returned in accordancewith the result of the error detection. If NACK is returned, which meanscorrect control information has not been transmitted, the transmittingwireless communication apparatus can stop transmitting the trafficchannel TC in the same manner. In the case in which the first and secondcontrol information C1 and C2 to which CRC is attached are transmitted,ACK and NACK can be returned in accordance with the result of the errordetection.

According to an embodiment, in the case in which CRC is attached toeither the first control information or the second control information,ACK may be set to “0” and NACK may be set to “1”. In the case in whichCRC is attached to both the first and second control information C1 andC2, ACK1 for the first control information C1 may be set to “00”, NACK1for the first control information C1 may be set to “01”. Similarly, ACK2for the second control information C2 may be set to “10”, and NACK2 forthe second control information C2 may be set to “11”. According toanother embodiment, another channel can be provided for transmitting ACKand NACK corresponding to the cases shown in FIGS. 9A-9C from thereceiving wireless communication apparatus. In response to receipt ofNACK, the transmitting wireless communication apparatus can stoptransmitting the traffic channel TC, and re-transmit the first controlinformation C1 and/or the second control information C2.

FIG. 10 is a block diagram showing a wireless communication apparatusthat can transmit and receive the first control information to which theCRC is attached. 51 and 52 denote antennas, 53 denotes a wirelessreception unit, 54 denote a wireless transmission unit, 55 denotes a TCdemodulation unit, 56 denotes a error correction decoding unit, 57denotes a C1 demodulation unit, 58 denotes a C2 demodulation unit, and59 denotes an error detection unit. This wireless communicationapparatus can be used as a mobile terminal of a mobile wirelesscommunication system.

The number of antennas 51 and 52 equals to that of MIMO multiplexing N.The wireless reception unit 53 is provided with a MIMO decodingprocessing unit (not shown) that receives a MIMO multiplexed signal,demodulates the signal, and separates the signal in accordance with thenumber of MIMO multiplexing N. The wireless reception unit 53 can bedesigned based on various known techniques. The wireless transmissionunit 54 can be designed based on various known techniques that generatesinformation series corresponding to the antennas and converts theinformation series into radio frequency.

As shown in FIG. 9A, in a wireless communication system in which thefirst control information C1 to which CRC is attached is transmitted, asignal is received by a wireless reception unit 53. Then, the firstcontrol information C1 is demodulated by a C1 demodulation unit, andchecked by an error detection unit 59. If the first control informationC1 is correct, a wireless transmission unit 54 returns ACK=“0”, but ifthe first control information C1 is found erroneous, the first wirelesstransmission unit 54 returns NACK=“1”. In response to receipt of ACK, atransmitting wireless communication apparatus such as a base stationtransmits the second control information C2 and the traffic channel TC.However, when receiving NACK, the transmitting wireless communicationapparatus re-transmits the first control information C1.

In response to the second control information C2 after receiving thefirst control information, the second control information C2 isdemodulated by a C2 demodulation unit 58. The traffic channel TC isdemodulated by a TC demodulation unit 55 in accordance with thedemodulated second control information C2. An error correction decodingunit 56 performs error correction and decoding on the traffic channelTC. If NACK is returned, since the second control information C2 is notdemodulated, processing by the TC demodulation unit 55 and the errorcorrection decoding unit 56 are suspended. According to an embodiment,power to the TC demodulation unit 55, the C2 demodulation unit 58, andthe error correction decoding unit 56, for example, may be suspended inorder to reduce power consumption.

FIG. 11 shows a wireless communication apparatus that can transmit thesecond control information C2 to which CRC is attached. The samereference numerals as those shown in FIG. 10 denote the same elements,respectively. Although multiple antennas 51 are provided, only one ofthem is shown to make the drawing simple. Similarly, although multipleantennas 52 are provided, only one of them is shown. In the case of awireless communication system in which the second control information C2to which CRC is attached is transmitted as shown in FIG. 9B, thewireless reception unit 53 receives a signal. The first controlinformation C1 is demodulated by the C1 demodulation unit 57. The secondcontrol information C2 is demodulated by the C2 demodulation unit 58,and the demodulated second control information is checked by the errordetection unit 59 using the CRC. ACK or NACK is returned by the wirelesstransmission unit 54 depending on the result of the error check in thesame manner as the previous example. If the second control informationC2 is correct and ACK is returned, the TC demodulation unit 56demodulates the traffic channel TC, and the error correction decodingunit 56 decodes the demodulated data from the TC demodulation unit 56.If the second control unit C2 is incorrect and NACK is returned,processing by the TC demodulation unit 55 and the error correctiondecoding unit 56 are suspended.

FIG. 12 is a block diagram showing a receiving wireless communicationapparatus in the case in which CRC are attached to the first and secondcontrol information C1 and C2. The same reference numerals as thoseshown in FIGS. 10 and 11 indicate the same elements. In FIG. 12, 60denotes a error detection unit, and 61 denotes a Ack/Nack signalgeneration unit. The error detection unit 59 performs error detection ona demodulated signal from the C1 demodulation unit 57 using CRC attachedto the first control information C1. The error detection unit 60performs error detection on the demodulated signal from the C2demodulation unit 58 using the CRC attached to the second controlinformation C2. The Ack/Nack signal generation unit 61 sets ACK1 for thefirst control information C1 to “00”, NACK1 for the first controlinformation C1 to “01”, ACK2 for the second control information C2 to“10”, and NACK2 for the second control information C2 to “11”, forexample, as described above. The generated ACK or NACK is returnedthrough the wireless transmission unit 54.

In response to receipt of ACK1, for example, a transmitting wirelesscommunication apparatus transmits the second control information C2. IfNACK1 is received, the first control information C1 is re-transmitted.If ACK2 is received, the traffic channel TC is transmitted. If NACK2 isreceived, the second control information C2 is re-transmitted.

In the case of a wireless communication system using OrthogonalFrequency Division Multiplexing (OFDM) or multi carrier, the firstcontrol information C1 and the second control information C2 for oneframe can be disposed in a time-frequency domain as shown in FIG. 13,where the horizontal axis corresponds to time and the vertical axiscorresponds to a sub-carrier. In the case of a CDMA system, sincemultiple spreading codes can be selected, the physical resourceincluding frequency, time, and spreading code can be allocated to thefirst control information C1 and the second control information C2 inaccordance with their amount by adapting CDMA system to OFDM system.According to another embodiment, the MIMO system may be combined withthe OFDM system, the CDMA system, and the Space diversity system. Insuch a case, information indicating the transmission system is includedin the first control information C1 thereby to allow the second controlinformation C2 and the traffic channel be received.

All wireless communication apparatuses in a wireless communicationsystem are required to know the adapted transmission system such as theMIMO system. If the information is given to all users, the systemstructure can be varied. In such a case, a notice channel can be usedthrough which all the users can receive the information. For example,the first control information C1 only needs to be available at the timewhen the traffic channel TC is received. The first control informationC1 may be transmitted through the notice channel thereby to make allusers noticed. In addition, before data is transmitted through thetraffic channel TC, the first control information C1 may be transmittedas a part of control information of a upper layer.

FIG. 14 is a block diagram showing a wireless communication apparatus inthe case the first control information C1 is transmitted through anotice channel. In FIG. 14, 70 denotes a multiplexing unit, 71-74 denotespreading units, 75 denotes an addition unit, 76 denotes a wirelesstransmission unit. These elements corresponds to an antenna 1 amongmultiple antennas. The transmission format information of the firstcontrol information C1 is multiplexed with other notice information bythe multiplexing unit 70 and input to the spreading unit 74. The antenna1 transmission symbol (TC(1)) of the traffic channel TC is input to thespreading unit 71. The antenna 1 transmission symbol (CC(1)) of thecontrol information CC is input to the spreading unit 72. The antenna 1pilot symbol (P(1)) is input to the spreading unit 73. The symbols arespread using different spreading codes, and added by the addition unit75 chip by chip. The symbols are modulated for the antenna 1 andtransmitted by the wireless transmission unit 76. The notice informationis transmitted from the base station of the mobile wirelesscommunication system. The mobile terminal can know the transmissionformat of the first control information C1 based on the received noticeinformation, and receive the second control information C2 and thetraffic channel TC.

The present invention is not limited to these embodiments, but variousvariations and modifications may be made without departing from thescope of the present invention.

This patent application is based on Japanese Priority Patent ApplicationNo. 2004-360878 filed on Dec. 14, 2004, the entire contents of which arehereby incorporated by reference.

What is claimed is:
 1. A mobile terminal, comprising: a receiving unitthat receives from a base station, first control information includingcontrol information regarding Multiple Input Multiple Output (MIMO),second control information to which first transmission processing inaccordance with a content of the first control information regardingMIMO is applied at the base station, and data to which secondtransmission processing in accordance with the first control informationand the second control information is applied at the base station,wherein the content of the first control information specifies whetherMIMO mode is to be applied or not, and the second control informationincludes Hybrid-ARQ process information, redundancy and constellationversion information, and transport block size information, wherein atransmission rate of the second control information is variable.